JP4040103B2 - Wave energy extraction - Google Patents

Description

Technical field
The present invention primarily relates to a system for powering natural energy and converting energy from waves into an easy to use energy format such as electric power.
In particular, the present invention relates to a wave energy extraction system and components thereof that use a wave up-and-down motion to deliver a large amount of air to a wind turbine coupled to a generator. In a preferred form of the invention, the waves are sent to a specially configured air compression chamber. A wind turbine that operates as appropriate is disposed in the exhaust port of the air compression chamber.
To this end, the various aspects of the present invention provide a novel collector, an air compression chamber arrangement that is particularly suitable for use with the novel collector, and the periodicity described above. And an independent novel wind turbine that operates to rotate in one direction under normal reciprocating airflow conditions.
Although various aspects of the present invention are described herein in combination to form a complete energy conversion system, each of these components, particularly turbine components, is also suitable for use in other unrelated applications. Please understand that there is. Alternatively, each may be incorporated into a similar energy conversion system when combined with other new or existing component devices not described in detail in this document.
Background of the Invention
Environments such as waves, winds, tidal currents, geothermal and solar heat, due to the limited resources of conventional combustible hydrocarbon fuel sources and the concern about the harmful waste produced by using such fuels Considerable research has been conducted on energy sources that can be sustained without polluting the environment.
While significant technological progress has been made in converting energy from others such as wind and solar heat, the majority of wind power systems proposed to date lack physical utility and / or Or it is not economically practical.
In view of this, a number of different types of wave power systems have been proposed, most of which are based on the basic principle using vertical motion inherent to wave motion, and the components of the power system accordingly. It is displaced. However, all the proposed systems have limitations.
For example, one such system uses a floating body that vibrates and converts its motion directly or indirectly into electrical power. However, these floating systems typically have poor energy conversion efficiency and cannot withstand bad weather conditions. This means that such systems are limited to use in coastal areas where the wave pattern is calm and predictable, or protect the system with a suitable shelter when a storm appears to come .
Other systems include those based on concepts such as carrying waves through drainage pumps or storing water in large tanks or reservoirs and using the hydrostatic pressure of this stored water to drive turbine generators. Again, the overall energy conversion efficiency is relatively low at the expense of associated investment costs.
Of the other types of options proposed so far, one of the most promising alternatives is also the basis of the present invention, converting wave vertical movements into rotational movements directly or directly It indirectly drives the generator. In these systems, the vertical movement of seawater is transmitted and motive power is generated in the air compression chamber. The air compression chamber has an exhaust duct or venturi on the outlet side, in which a kind of wind turbine operable to rotate in one direction under a periodic oscillating air flow generated by wave motion is arranged. Yes.
Again, the main drawback of such latter wave-driven air turbine system is that the overall achievable energy efficiency is limited. This is mainly due to the operational efficiency which is unavoidable in the design of this turbine, firstly, the means for collecting the wave energy to the maximum wave displacement amplitude is limited.
In the first case, most of the prior art collectors rely on the wavefront rebound and / or movement of the wavefront through a narrow aperture so that the vertical displacement or amplitude of the wave is increased. ing. Others include various means of changing the shape of the seabed and blocking the wave propagation while controlling it, thereby maximizing the wave amplitude at a predetermined location. Again, this type of system is so far limited in terms of the maximum wave amplitude that can be achieved instead of a certain level of capital investment.
In the second case, most of the prior art turbines are designed to rotate at a constant speed in response to fluid flow in only one direction, and are themselves applications of wave power generation of the kind described above. It is impossible to perform continuous operation in response to the reciprocating fluid flow conditions that occur in However, a number of specially configured one-way turbines have been designed for these reciprocating flow conditions, and the most commonly used equipment is based on what is known as a “Wells” turbine.
The original Wells turbine has blades whose airfoil sections extend in a radial direction that is substantially symmetrical about the chord line, and these blades are lifted perpendicular to the axis of the blade and fixed to the blade surface at zero. It was a monoplane axial flow type structure.
However, these early turbines were known to have stall problems, which caused the wave energy power plant to shut down. This stall has to be designed around the predicted airflow level for such turbines, but this is due to the fact that it is impossible to control the waves entering the turbine air chamber in all cases. Is. Thus, when a large wave enters the air chamber, the moment causes fairly high speed air to pass through the turbine blades. The blade shape increases the rotation speed of the blade correspondingly and cannot cope with the increased air flow. Therefore, the angle of attack of the air flow with respect to the blade increases, exceeds the stall angle, and the turbine stops. .
In the latter prior art device, two monoplane wells turbines were installed efficiently in series to obtain a bi-plane turbine, and an attempt was made to overcome the above problems. There is something. Such a partially modified system solves the problem of stalling, but at the cost of lower overall efficiency. This is done by sacrificing the first set of blades by allowing the first set of blades to stall and stop accordingly, while continuing to operate at a reduced pace and efficiency with the second set of blades. Because it is. This is because the air flow as a whole is reduced and blocked by the first turbine stalling and shutting off the air flow.
These prior art turbines also typically rely on low rotation, high mass configurations to provide smooth continuous rotation under conditions where periodic reciprocating airflow of the type described above is supplied.
It will therefore be appreciated that most prior art turbines suitable for this type of application are often very complex in design and usually have severe constraints on operating conditions and / or efficiency.
It is an object of the present invention to overcome or at least reduce one or more of the disadvantages of the prior art described above, or at least be a useful alternative to these wave energy extraction systems and / or one or more thereof. To provide multiple components.
Disclosure of the invention
According to the first aspect of the present invention, the boundary is defined by a substantially upright wall configured to define two convergent side walls having a substantially partial parabolic curvature at the inner periphery from the bay inlet. The parabolic axes of the parabolas on the extension of the wall are parallel, the side walls are joined adjacent their converging ends to form a common top, and the walls are substantially parallel to the symmetrical axis. Placed in a direction to accept traveling waves propagating in parallel directions, when the waves bounce off the wall, the waves are in the energy-powered region near the top at the position of each focal point of the parabola or adjacent to the focal point. By converging, a plane wave collecting and amplifying structure that amplifies the vertical displacement of the wave in that region is obtained.
Preferably, converging sidewalls of partial parabolic curvature are joined at a common top by an end wall portion that also defines the rear wall portion of the air compression chamber, and the front wall of the compression chamber extends in front of the rear wall portion. The front wall cross-section is defined by the cross-section and defines a predetermined area boundary around the energy-powered region so that the water forming the wave flows under the front wall and up the compression chamber Only a part extends below the water level.
In a preferred form, the wall is configured to define a single parabola or an end portion of a shape very similar to it at the inner circumference in a planar cross section, and when the wave bounces off the wall, the wave It converges at the single focal position of the parabola or at the area adjacent to it.
In another form, which may keep the construction cost low, the structure is equipped with an air compression chamber, the rear wall part is partly formed by the existing coastline, and the partial parabolic curvature extends from the wall of the compression chamber. The bay may simply be defined by two possible relatively short side walls having Usually, any compromise on the length of the parabola-curved sidewall is compensated by extending the planar area of the air compression chamber that defines the boundary of the energy-powered region.
Preferably, the bay boundary is further defined at the bottom of the bay by a substantially flat seabed at a certain depth along a direction substantially perpendicular to the axis of symmetry of the parabola. The depth of the seabed and the slope (if there is a slope) can vary depending on the local formation, wave conditions and how the amplified waves are motivated for energy extraction. The general goal is to optimize local conditions so that ideally the wave magnification can be maximized without breaking before entering the motorized region. For example, in a preferred form, the seabed may be tilted upward toward the motorized area and helped to collect water upwards at that location.
Preferably, the focal length of the parabola is 1/7 or less of the approach wavelength, which in many cases results in a focal length of 5-15 meters.
According to a second aspect of the present invention, a turbine that is operable to rotate in one direction when a substantially axial reciprocating fluid flow passes and includes a blade, the blade comprising:
A central hub,
A plurality of blades having a cross-sectional airfoil extending straight in a radial direction and each connected to the hub,
The cross-section of each of the blades is substantially symmetric about a line defining a maximum warp height, and is substantially constant from end to end in the radial direction;
This provides a turbine in which the generally symmetric shape of the blade orientation relative to the blade and hub facilitates rotating blades in one direction in response to an axial reciprocating fluid flow through the blade.
Preferably, each blade is connected to the hub such that the maximum internal angle between the chord surface of the airfoil section and the axis of the hub is 0 ° to 90 °, more preferably 0 ° to 45 °, for example. Yes.
Desirably, the aforementioned maximum interior angle is adjustable and can preferably be reversed in synchronism with the reciprocating fluid flow, thereby optimizing the angle of attack for fluid flow in both directions.
It should be understood that blade pitch reversal can be accomplished in a variety of ways, for example, using a motor driven bevel gear assembly arranged to rotate a central spigot on which each blade is mounted. In another variant, each blade is mounted on a spigot having an offset working side wall that cooperates with a helically keyed working shaft that is reciprocable along the axis of the blade. .
In a preferred form suitable for a particular combination of conditions, the maximum interior angle is between -30 ° and + 30 ° and is reversible in response to reciprocating fluid flow. In another preferred form that is particularly suitable for applications of the type described herein where the working fluid is a gas such as air, the reversal of the blade pitch is a pressure arranged to detect the reversal point of the gas flow. By means of responding to the transducer.
Desirably, the blades are arranged at equal intervals around the central hub. In some preferred forms suitable for a particular application, the blade includes 4 to 16 blades. The chordal ratio can be changed in a wide range and is often included in the range of 0.2 to 0.8. The preferred blade chord ratio is 18% and the preferred airfoil comprises a merged form of the front half of a standard NACA 65-418 airfoil.
According to a third aspect of the invention,
A wave collecting means for enlarging a periodic vertical peak to obtain a wave-bottom displacement of an incoming wave at a predetermined plane position;
A periodic reciprocating air that has a water intake port submerged substantially in water, and is disposed at the predetermined plane position or immediately adjacent thereto, and a large amount of air is displaced on the position. An air compression chamber for receiving periodically oscillating waves so that a flow is generated,
A wave energy extraction system is also provided which also has an air outlet with an air driven turbine in which the compressed air chamber operates to rotate in one direction in response to the reciprocating air flow.
Desirably, the turbine is constructed in accordance with the second aspect of the present invention.
Preferably, the wave collecting means includes the substantially parabolic plane wave collecting and amplifying structure according to the first aspect of the present invention, and the apex of the parabola falls within a predetermined plane position.
Desirably, the air compression chamber is configured to converge from the water intake port toward the exhaust port so as to accelerate the air flow. In a preferred form, the air compression chamber includes a venturi adjacent to its exhaust and an air driven turbine is located in the neck of the venturi.
In another preferred form, the air compression chamber exhaust and / or shroud and / or vane associated with the turbine may include guide vanes for optimizing the direction of air flow into and out of the turbine.
[Brief description of the drawings]
Hereinafter, a preferred embodiment of the present invention will be described as an example with reference to the drawings.
FIG. 1 shows a first embodiment of a concentrating amplification structure according to the first aspect of the present invention, wherein the side wall from the cove is formed by two partial parabolic portions having parallel and spaced apart axes of symmetry. It is a schematic plan view.
FIG. 2 shows a plane wave converging amplification of a second embodiment according to the first aspect of the present invention in which the wall is substantially defined by the end of one parabola and shows the maximum wave trough displacement achievable in the motorized region. It is a schematic perspective view by the computer production | generation of a structure.
FIG. 3 is a computer-generated schematic perspective view of the structure shown in FIG. 2 showing the maximum wavefront displacement obtained in the energy-powered region.
FIG. 4 is a reduced graph of the parabolic plane wave collecting apparatus of the second embodiment as shown in FIGS. 2 and 3.
FIG. 5 is a schematic cross-sectional view of the plane wave partial parabolic concentrating amplification structure of the third embodiment.
FIG. 6 is a schematic perspective view of a turbine blade of the first embodiment according to the second aspect of the present invention, in which the blade is fixed to the central hub shaft at an internal angle of 0 °.
FIG. 7 is a schematic of a turbine blade of a second embodiment according to the second aspect of the present invention where the blade pitch is adjustable and the pitch can be reversed in response to reciprocating air flow through the turbine. It is a perspective view.
FIG. 8 is a partial view of the turbine blade of FIG. 7 showing one blade and a connecting portion of the blade to the hub.
FIG. 9 is a schematic cross-sectional view of one blade of the turbine blade shown in FIGS. 6, 7 and 8.
FIG. 10 is a schematic cross-sectional view showing a blade pitch change reversal mechanism of the turbine of the first embodiment.
FIG. 11 is a partial plan view of the mechanism shown in FIG.
FIG. 12 is a schematic diagram showing a blade pitch change reversal mechanism of the turbine of the second embodiment.
FIG. 13 is a partial plan view of the mechanism shown in FIG.
FIG. 14 is a schematic cross-sectional view of the wave energy extracting apparatus according to the first embodiment of the third aspect of the present invention.
Preferred embodiments of the invention
Referring first to FIG. 1, there is shown a collecting structure of a first embodiment according to a first aspect of the present invention, generally designated by the reference numeral 1.
The structure 1 includes an entrance 2 formed by a tide wall 3 that is substantially upright. The wall 3 is concavely curved at the inner peripheral portion 4 thereof, and defines two converging side walls 5 having a substantially partial parabolic curvature by a plane. The respective axes of symmetry 6 and 7 of the parabola on the extension of the side wall are parallel to each other. The side walls 5 are joined adjacent to their convergent ends to form a common top 8. The wall 3 is arranged in such a direction as to accept a traveling wave propagating in a direction substantially parallel to the symmetry axes 6 and 7.
Figure 5 shows that it would be too expensive or impossible to build a wall in the bay that has a long parabolic side wall that extends outwardly towards the bay as part of the surrounding coastline FIG. 5 shows another variation of the structure shown in FIG. In this case, a parabolic side wall 5 composed of a relatively short portion directly connected to the common top portion 8 is formed, whereby a wall portion of the air compression chamber indicated by 11 in the cross-sectional view is formed at the same time as a compromise.
2, 3 and 4 show a preferred form in which the structure is formed as a single parabola with a single focal point 9 or an end portion of a shape very close to it.
Ocean waves have enormous amounts of energy, but are usually plane waves, so the energy at each wave front is dissipated along the wave front. The purpose of the parabolic or partially parabolic collecting structure according to the first aspect of the present invention is to move or converge this energy to one central region from which it can be energized. is there.
In use, the wave collecting structure is oriented as described above so that the plane wave advances in a direction substantially parallel to one (or both) of the symmetry axes 6 and 7 toward the parabolic or partially parabolic wall 3. Is arranged in. When hitting the parabolic part 5 of the wall 3, the waves bounce back and converge towards the corresponding focal point 9 or 9 and 10 of each parabola. If the wall defines a part of a single parabola as shown in the second preferred embodiment of FIGS. 2, 3 and 4, the wave will travel to a single focal point 9 as a circular or polar wave. To converge. At this point, the wave displacement amplitude becomes considerably larger, and this point becomes a perfect plane position where a suitable means for converting the seawater displacement into another more readily available energy form is installed. This is defined in FIG. 5 as an energy kinetic region, generally indicated at 12, corresponding to the position of the air compression chamber 11. Obviously, the size of this area in the plane is not particularly determined and is determined in part by the energy dissipation achieved in this area.
It should be noted that there are several conditions that must be satisfied in order to maximize energy recovery using the above-described substantially parabolic or partially parabolic collecting amplification structures.
First, the wave crest must propagate in an ideal way that is nearly parallel to the symmetry axes 6 and 7 of each parabola. Slight fluctuations may be acceptable with only a small loss of energy, but as the angle between one or more symmetry axes and the wave propagation direction increases, more energy is dissipated in the energy concentration area. Exists and the system becomes inefficient. Since the water depth gradually becomes shallower along the coast and the incident angle of the wave does not change greatly, it is not usually of great concern to install the wave collecting structure in the correct direction.
Ideally, after the portion of the plane wave has entered the parabolic domain, the seabed should be flat or planar through the axis of the parabola and be deep enough to avoid disturbing the direction of the wave. . Alternatively, in other cases, the ocean floor is configured so that it does not break before entering the motorized region when the crest grows due to non-linear effects. Preliminary studies have shown that a depth of about 6 meters at the bay is sufficient for one particular application, but this is greatest under swell conditions.
If the energy is initially dispersed due to a very large triangular wave or an irregular approach wave, the energy is also somewhat dispersed from the focal point 9 or 9 and 10. The energy loss due to this or the energy loss due to any of the above-mentioned conditions is reduced by appropriately selecting the focal length so as not to give the wave a time or spatial allowance that changes significantly within the parabolic domain. It is possible. Again, preliminary studies have shown that a focal length of about 1/7 wavelength is appropriate for various applications. Since the wavelength is generally 35 to 105 meters, it is about 5 to 15 meters in terms of focal length.
This type of concentrator has great potential, and it is a computer simulation that 24% more energy flows into the parabolic domain than is present in a non-aggregated wave of a length corresponding to the opening width of the parabola. It is clear from This is a calculation where the wave is about tripled. In the test on the data, it was found that a magnification of 2.5 can be easily obtained.
However, due to the actual loss, the maximum theoretical energy level is not reached. For example, when actually operating a single parabolic structure, a circular wave converging at the focal point will not actually be a perfect circle because there are sectors lost on the open ocean side. At the edge of this lost sector, there is some energy diffraction into the parabolic domain. There are also losses due to interference reflections from coastal structures located adjacent to parabolic bays and irregularities in the sea floor.
The preferred means for accomplishing the above energy extraction and conversion will now be described with reference to the second and third aspects of the invention and the associated FIGS. 6-14.
Referring to FIG. 6, there is shown a turbine blade 20 of a first embodiment turbine according to a second aspect of the present invention operable to rotate in one direction when a substantially axial reciprocating fluid flow passes. ing.
The blade 20 includes a central hub 21 having an axis 22. Extending from this axis are a plurality of blades 23 of airfoil cross-section extending straight in the radial direction.
Desirably, blade 23 has a generally contoured airfoil cross-section as shown in FIG. 9 with a generally flat surface 24 on one side and a generally convex surface 25 on the opposite side. The entire chord line (also shown as the chord plane extending in the longitudinal direction of the blade is also shown) at 26. As shown in the figure, the cross section of each blade is also substantially symmetric about a line 27 defining the maximum warp height of the blade cross section, and is almost constant from end to end in the radial direction.
In the first embodiment shown in FIG. 6, the chord surface of each blade is arranged in a row or parallel to the central hub shaft 22 at an internal angle of 0 °. Thus, the air flow entering the turbine has the same incident angle with respect to the blade blade 23 regardless of the axial direction, and the rotation of the blade is the same as described above. In view of this, the net force exerted on the substantially flat blade surface 24 as the fluid passes is due to the Bernoulli effect and the pressure difference obtained between the flat and convex sides of the blade. The fluid flow from any direction is the same, and the magnitude depends on the relative air flow in the two opposite directions.
Such a fixed blade configuration is satisfactory for various applications at low speeds, but as the rotating speed of the rotor blades increases, the angle of attack of the drive flow becomes less optimal and increases the operating efficiency of the turbine. Influenced.
To address this problem, a second variable pitch embodiment of the present invention is proposed as shown in FIGS. In this embodiment, each blade 23 is connected to the central hub 21 by a central spigot 28 or the like. The spigot facilitates blade rotation and changes pitch by a suitable intermediate mechanism.
Preferably, the mechanism for adjusting the blade pitch is configured so that the pitch automatically reverses in synchronism with the reciprocating fluid flow through the blade and the angle of attack is optimized in both directions. Please be careful. Obviously, if the blades are fixed so that they are optimized in only one direction, the reversal of airflow will most likely provide any benefit that can be obtained with the fixed parallel blade configuration shown in FIG. It will have more negative effects than offsetting.
10 to 13 show two preferred mechanisms as an example. In view of this point, FIGS. 10 and 11 show a simple arrangement in which each blade 23 is fixed to a spigot 28 located in the center by a sleeve 29 and this spigot is fixedly connected to a hub 21 of a moving blade. . Similarly, fixedly connected to the hub 21 is a suitable motor 30 for driving a pinion gear 31 suspended in the axial direction. The pinion engages with a spur gear 32 having an associated annular bevel gear 33 that is freely rotatable about the central hub 21.
A bevel gear 34 that is smaller than the sleeve and engages with an annular bevel gear 33 is provided at the end of the sleeve 29 of the spigot 28 in the center of the blade 23. A similar arrangement is made for each blade. In this way, even while the turbine is rotating at high speed, the inclination of the blade relative to the axis of the blade can be changed by the gear mechanism described above.
FIGS. 12 and 13 show another arrangement in which the rotation of the blade 23 is achieved by an axial reciprocation of an actuating collar 35 keyed in a diagonal direction. This collar keyway engages an engagement pin 36 attached to the offset actuation side wall 37, thereby rotating the blade about the central spigot 28.
Those skilled in the art of turbine design will appreciate that there are many parameters that need to be evaluated for specific conditions and energy content for each proposed application of this type of turbine. These parameters include blade aspect ratio (chord ratio), blade chord length, turbine chord ratio (effectively blade length to hub diameter ratio), number of blades, blade airflow direction. For example, the maximum angle (ie, blade pitch) that can be directed. An example proposed as suitable for one particular application is a blade chord ratio of 18%, a chord length of 0.4 inches, a hub diameter of 1.2 meters, a blade length of 0.45 inches, for a total of 12 In the blade, the maximum internal angle between the chord surface of the blade and the hub shaft is 30 °. A preferred airfoil includes a merged form of the front half of a standard NACA 65-418 airfoil.
Turning now to FIG. 14, there is shown a schematic cross-sectional view of a first embodiment of the wave energy extraction system 40 according to the third aspect of the present invention.
The system 40 has collecting means indicated generally at 41. This wave collecting means is used to increase the periodic vertical peak to obtain the wave-bottom displacement of the approach wave at a predetermined plane position whose center is indicated by a line 42, that is, the motorized region 12.
It is the air compression chamber 43 that is located at the location of the planar position 42 that delimits the motorized region or at a location immediately adjacent thereto. The compression chamber has a water inlet 44 submerged substantially in water, and is sized so that a large amount of air 45 is displaced to generate a corresponding reciprocating air flow when a periodic vibration wave flows.
Desirably, the compression chamber converges toward an exhaust port 46 provided with or adjacent to an air driven turbine, indicated generally at 47.
In use, the incoming wave is collected so that the periodic vertical peak can be increased adjacent to the position 42 to create a wave bottom displacement. In this way, the reciprocating body or the water column vibrates in the air compression chamber 43 through the water suction port 44, whereby the air 45 acts like a piston. For example, at the time of a close wave, the air 45 is displaced toward the exhaust port 46, approaches the wall of the compression chamber and the duct, and accelerates the displaced air flow. The air flow thus accelerated can be forcibly sent to an air-driven turbine, and the rotation can be used at a power plant or the like. During a pulling wave, air is pulled downwards into the compression chamber and re-rotates the turbine configured to operate in one direction in response to the reciprocating air flow.
In a preferred form, the system utilizes the parabolic concentrator of the first aspect of the invention and the one-way turbine according to the second aspect of the invention. Thus, by combining the excellent efficiency of each of these mechanisms, a wave energy extraction process with extremely high practicality can be obtained.
However, as indicated above, each component of this system, particularly the concentrator and turbine, can each be used in other applications or in combination with other devices not described in detail herein. Obviously, you can do that too. This is particularly relevant for turbines having a large number of unrelated applications that are used with various working fluids.
Thus, in brief summary, although aspects of the invention have been described with reference to specific examples, each of these various aspects, and particularly combinations of systems incorporating these aspects, can have various different forms. It will be apparent that both are included within the scope of the embodiments of the invention claimed below.

Claims (15)

A turbine that is operable to rotate in one direction when a reciprocating gas flow in a substantially axial direction passes and includes a blade, wherein the blade is
A central hub,
A plurality of blades having a cross-sectional airfoil extending straight in a radial direction and each connected to the hub,
Each of the blades includes an opposing non-parallel surface and a tip having a continuously bent surface;
The cross-section of each of the blades is substantially symmetric about a line defining a maximum warp height, and is substantially constant from end to end in the radial direction;
The orientation of the blade relative to the hub and the nearly symmetrical shape of the blade make it easier for the blade to rotate in one direction in response to the axial reciprocating gas flow through the blade,
Turbine characterized in that the pitch of the blades is reversible in synchronism with the reciprocating gas flow, the reversal of the blade pitch being achieved by means responsive to a pressure transducer arranged to detect the reversal of the gas flow . The turbine according to claim 1, wherein each of the blades is connected to the hub such that a maximum internal angle between a chord surface of the airfoil cross section and a shaft of the hub is 0 ° to 90 °. The turbine according to claim 1, wherein the blade pitch is variably adjustable. 4. A blade pitch changing or reversing mechanism comprising a suitably driven bevel gear assembly mounted with the hub and arranged to rotate each blade about a central spigot attaching the blade to the hub. The turbine described in 1. Includes a blade pitch change or reversal mechanism, each blade is attached to a spigot having an offset motion side wall that cooperates with a diagonally keyed actuation shaft that is reciprocable along the axis of the blade 4. The turbine according to claim 3, wherein the blade is rotated about the spigot. The turbine according to claim 1, wherein the maximum pitch or interior angle is between −30 ° and + 30 °. The turbine according to claim 1, wherein the rotor blade includes 4 to 16 blades. The turbine according to claim 1, wherein a chord ratio of the turbine is in a range of 0.2 to 0.8. The turbine according to claim 1, wherein the blade chord ratio is 18%. The turbine of claim 1, wherein the airfoil comprises a merged shape of the front half of a standard NACA 65-418 airfoil. The turbine is part of a wave energy extraction system;
The wave energy extraction system comprises:
A wave collecting means for enlarging a periodic vertical peak to obtain a wave-bottom displacement of an incoming wave at a predetermined plane position;
A periodic reciprocating air that has a water intake port submerged substantially in water, and is disposed at the predetermined plane position or immediately adjacent thereto, and a large amount of air is displaced on the position. An air compression chamber that accepts periodically oscillating waves so that a flow is generated;
Including
The compressed air chamber also has an exhaust port;
The turbine according to claim 1, wherein the turbine is provided in the exhaust port. The turbine according to claim 11, wherein the air compression chamber converges from a water intake port toward an exhaust port so as to accelerate an air flow. The turbine of claim 11, wherein the air compression chamber includes a venturi adjacent to an exhaust thereof, and the air driven turbine is located in a neck of the venturi. The turbine of claim 11, wherein the air compression chamber exhaust and / or shroud associated with the turbine includes guide vanes for optimizing the direction of air flow into and out of the turbine. A turbine that is operable to rotate in one direction when a substantially axial reciprocating fluid flow passes and includes a blade, wherein the blade comprises:
A central hub,
A plurality of airfoil blades that extend radially straight and each connected to the hub;
Each blade is attached to a spigot having an offset motion side wall that cooperates with a diagonally keyed actuation shaft that is reciprocable along the axis of the blade, thereby allowing the blade to be centered about the spigot. A rotating blade pitch changing or reversing mechanism, and
The cross-section of each of the blades is substantially symmetric about a line defining a maximum warp height, and is substantially constant from end to end in the radial direction;
A turbine in which the blades tend to rotate in one direction in response to an axial reciprocating fluid flow through the blades due to the orientation of the blades relative to the hub and the generally symmetrical shape of the blades.

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